Apparatus for cleaning paper for printing



Jan. 7, 1958 P. s. ROSEWALL APPARATUS FOR CLEANING PAPER FOR' PRINTING Filed Sept. 11, 1953 AXMO , INVENTOR. PAUL S- ROSEWALL ATTORNEYS- or otherwise compacted. ,to provide such anti-ofiset protection after one side of -,,paper has. been printed and it is proposed to print upon .,the other side. Powdered starch is widely used as an-anti- ,offset means, the starch being in finely divided form, .gen-

erally of the order .of from to 50 microns in diameter. --Q ther granular material may be used. As arule, the ,powdered starch or other material is disposed in athin layer generally uniformly distributed over-the paper surface. One convenient manner of applying such powdered starch is disclosed and claimed in-Patent 2,394,656 issued February 12, 1946 to Beregh. In this prior patent, means paper, or to the printing surface.

Paul S. Rosewall,- Chicago,-]1l., assignor to Oxy-Dry .Sprayer Corporatiom'ChicagO, '-Ill., a corporation of ,New York Application September 11, 1953,.Serial No. 379,593

. 6 .Claims. (Cl.--306) This invention relates to an apparatus'for cleaning paper for printing, and, particularly for removing anti-offset powdered material-or other dust-ordirt from paper prior ..to.printing.

It is customary to provide anti-oflset means on the .surface of printed paper to prevent smudging 'of the ink when the freshly printed stock is being stacked or rolled It is also frequently desirable are provided for electrifying and sifting particles of starch ,or other material .on the paper.

It is frequently desirable .to .run such coatedpaper through a printing press for additional printing. Thus one .-side.of a continuous web of paper may be printed and then .lprovided with anti-offset material, after which it may -be desirable. to print matter upon the other side of such ,,coated paper, all .as part of a continuous printing operation. It has been found that the presence of the antioffset material upon the paper stock seriously interferes with the proper operation of the press. Thus the printing .surfacesacquire a. coating of anti-olfset material and after a comparativelysmall number of impressions, it has been found necessary to stop the press and clean the printing surfaces. The same is true of inking rollers.

Various attempts have been made to remove the anti- ,olfset particles upon the paper prior to printing. Such attempts have failed or have resulted in damage to the Thus it isknown to provide suction nozzlesadjacent the paper surface for the purpose of removing dirt or any other loose material .moval of fine particles by prior means. As a rule, electrostatic forces exist because of the nature of the printing operation so that both the mechanical and electrical forces tending to retain particles against the paper are very considerable in relation to the weight of individual particles. Furthermore, the electrified particles, when originally applied to the paper, tend to strike the paper surfacewith substantial force and attach themselves tothe paper.

dahaveifound :that a combination of a blast of compressed. air, and a region of air turbulence and suction all Patented Jan. 7, 1958 in-proximity to the-paper-is effective for removingdirtand 1 particularly-anti-dflset materialfrom the surface of paper.

The compressed air-blast and suction region are both relatively close to the paper; The compressed air blast is directed against the paper to be cleaned, the reflected air entering aregion-where high turbulenceexists. The blast of air is generallystrongenough-to loosen some anti- .ofisetparticles and dislodge the same from the paper.

There is providedanenclosed region within which turbulent particle-filled air maintains the anti-offset particles inrsuspension until suction acts on the particlesto remove the same from the enclosed region.

In; its moregeneral .-aspect,=-theapparatus embodying the presentsinventionmay consist of-a unitaryaccessory whichmaytbelattached to a=printing press so as to act upon --the -paper.surface just prior to the printing. The accessory the ,airqblast, turbulence and. suction operate. The clearachncein;v general-will .depend upon such factors as paper tension and possible =vibration. of the paper'sheet, suction --pressureand-pressure of thecompressed air. In general, .aclearancepf between about hi to 1A of an inch has .-,an-;inch. is preferred.

. illustrated.

been-found to ,beeffective. A clearance of about A; of

Jnorder that the invention may be understood, it will now be explained in connection with .the drawings wherein an exemplaryconstruction embodying the invention is It .is understood, however, that substantial variations may bemade in the construction without de parting from the scope of the invention except as defined by the appended claims.

.Referring to the drawings;

1 Figure 1 is a diagrammatic representation of a portion of aprinting system showing paper having the invention applied thereto.

' Figure 2 is a transverse sectionaldetail showing the apparatus embodying the present invention.

Figure 3 is a detail of-the compressed air pipe forming part of the new construction.

Figure 4 is a detail of the suction nozzle means forming part of the apparatus embodying the present invention.

Referring first to Figure 1, there is shown paper-web it) travelling in the direction indicated, the paper'being suitably tensioned and passing by rollers 11 and 12. An additional tension roller 13 is provided, and between roliers 12 and 13 there is disposed printing cylinder 15. instead of cylinder printing, there may be providedilat press printing, offset printing, or any other type desired.

it is understood that paper web 10 may-be coated with anti-offset material and that the paper is coming either from a storage source or from a previous printing operation. While a continuous webfeed is illustrated, the invention may also be applied to sheet stock where, individual paper sheets are fed for printing. It is also possible that paper 10 is raw stock and has dirt thereon.

Disposed against a straight length of paper between rollers 11 and. 12 is paper cleaning attachment, generally indicated by 20. Attachment 20 consists ;of elongated housing 21 having sides 22 and 23 and bottom 24. Housing 21 extends the full width of the paper, the length of housing 21 extending across the width of the web, and may consist of any rigid material such as sheet metal or nonmetallic material such as fiber, any strong plastic or the like. Sheet metal, however, is preferred because it is light and strong.

Housing 21 has end Walls and isopen opposite tobottom 24. Housing 21 has itsdepth extending away from the web surface while the. width of. the. housingextends parallel to the direction of travel of the web. Sides- 22 and23-are provided with suitable material such as felt.

Thus strips 26 and 27 of felt may be attached, as by cement, rivets or the like to the inner surfaces of the housing sides. Felt liners 26 and 27 have portions 28 and 29 extending beyond the free edges of sides 22 and 23 respectively. Instead of felt, rubber or other material may be used. Felt, however, is convenient and economical. It is possible to omit the liners.

The depth to which the felt material extends within the housing may vary within wide limits and as illustrated here, the felt extends almost to the bottom of the housing. The thickness of the felt is not important except that it should be thick enough to be self-supporting at the free edges. The felt provides a convenient soft edge which will not damage the paper if contact occurs.

Suitably disposed within the housing are pipes 31 and 32. Pipe 31 is for compressed air and may be of substantially smaller diameter than pipe 32. In practice, pipe 31 may be of copper or brass, although any material, either metal or nonmetal, may be used. The pipe is suitably supported against one of the housing sides, in this instance side 22, pipe 31 being so located as to have one portion thereof near the open side of the housing. Pipe 31 is provided with a series of apertures 33 through which compressed air may escape. Apertures 33 are dis posed generally along a straight line parallel to the pipe axis. Apertures 33 are sufiiciently close so that at a short distance from the pipe the minute air blasts merge into a substantially continuous (along the length of pipe 31) blast near the open side of the housing. It will be noted from Figure 2 that pipe 31 is so oriented as to dispose air discharge openings 33 generally toward the open side of the housing and preferably somewhat inclined toward opposing housing side 23. The entire attachment is provided with suitable brackets 35 for mounting upon the press. Stifiener strip 36 is provided for reinforcing the housing.

As is indicated in Figures 1 and 2, the housing is secured so that paper will be disposed in proximity to the open side of the housing, the paper clearing the free edges of felts 26 and 27 by short distances as previously set forth. The clearance need not necessarily be the same for sides 22 and 23 and so long as the clearances remain generally within the ranges previously specified, satisfactory operation will occur.

Compressed air pipe 31 will provide blasts of air against paper 16. Pipe 31 may have one end 37 sealed and may have hose 38 supplying the other end of the pipe with the necessary compressed air. The diameters of apertures 33 will usually be small of the order of about of an inch and the spacing between adjacent apertures may be of the order of about Me inch or an inch. These figures, however, are exemplary and the size of the openings, and the spacing will depend upon the diameter of pipe 31, the pressure of the air supplied by hose 38, the distance between the discharge apertures 33 and the paper, and similar factors normally well within the scope of a mechanic.

If desired, the compressed air supply to pipe 31 may be at the two ends of the pipe or at the center or at any one of a number of points. Pipe 31 itself may generally have a diameter of about /2 inch or inch but this may also vary with the other factors previously itemized. The air pressure supply to pipe 31 may have any desired value within wide limits. The blast issuing from apertures 33 should not be great enough to deflect the paper excessively.

Pipe 32 is provided for drawing off air from within housing 21. Pipe 32 will be larger in diameter than pipe 31 to reduce the air flow resistance. Pipe 32 is provided with aligned slots 40, slots at being separated by small tongues 41 of pipe material. The tongues are provided merely to endow the pipe Wall with stiffness. Slots 46) taper in width from a maximum at one end of the pipe to a minimum at the other end of the pipe as illustrated in Figure 4. As shown in Figure 4, pipe 32 has end 42, which may be considered as a sealed end, and has end 43 to which hose 44 is attached. Hose 44 is connected to a suitable suction generating means such as, for example, a suction cleaner having sulficient capacity. It has been found that an industrial type of vacuum cleaner will generally be satisfactory.

As with air supply pipe 31, it is not essential that the suction be applied to one end of the pipe. It is possible to have suction manifolds coupled to the two ends of the pipes or coupled to intermediate portions of the pipe at the regions where the pipe is disposed in proximity to housing bottom 21. For convenience in controlling the suction, bleeder valve 45 may be provided.

The taper of slots 40 is convenient in the form of the invention illustrated, the decreasing resistance of the wide slots compensating for the reduced suction. If the suction tube is provided with more than one suction connection, then a different pattern of slot taper will be provided. Thus if the two ends of pipe 32 have suction applied thereto, then the widest suction slot will be mid way between the two ends of pipe 32 with the taper extending in both directions. Any other means for increasing the uniformity of suction pressure along pipe 32 may be utilized.

Suction tube 32 is secured in housing 21 in proximity to side 23 and bottom 24. The pipe is so oriented that suction slots 40 face in the general direction of the free edge of felt 29. Some variation in the orientation of pipe 32 is permissible. However, it is necessary to have slots 40 disposed in part 32a of pipe 32, this part extending away from paper 10 toward felt 27. Pipe 32 will normally be as large in diameter as possible while still being capable of being positioned within the housing. Both pipes 31 and 32 are shown as cylindrical. This, however, is not essential and either or both of these pipes may have other shapes, including rectangular. Cylindrical pipe, however, is readily available and easily handled.

Housing 21 has sufiicient width (the dimension be tween sides 22 and 23) so that the width is somewhat greater than the combined diameters of pipes 31 and 32. In general, the width between sides 22 and 23 will be somewhat greater than the depth, a ratio of between about 1 /2 to l and 2 to 1 being satisfactory. This may be varied, however, and the values are exemplary only. The width and depth of the housing are of the same order and may even be equal. A region generally indicated by 4-6 is formed within the housing and the outer surfaces of pipes 31 and 32. Within this region, violent air currents exist and maintain in suspended condition whatever particles are blasted from paper 10 by the air blast emerging from pipe 31. The shape of the housing is not important and instead of a rectangular housing, a semi-circular housing or a housing with curves instead of corners may be provided. However, region 46 extending for a substantial distance away from the surface of the paper is essential. This is a region of great turbulence with air currents probably whirling around in circular paths tangent to the paper surface.

The pressure within the housing and outside of pipe 31 will function as an aid to forcing air and suspended matter into suction pipe 32. It is possible that the violent air currents existing along the surface of paper 10 aid the blast in removing the fine particles from the paper. In any event, an air blast and suction region adjacent to the paper and separated by an enclosed region function effectively and efliciently to remove fine particles such as offset material from paper.

It will be noted that as seen in Figure 2, the curve of pipe 32 with respect to the surface of paper 10 produces a sort of venturi region 32b. It is possible that the intake to this venturi region is supplied with powder-laden air from turbulence region 46. The velocity of the powder at the smallest part of the venturi is a maximum and the high velocity powder particles along the paper surface may act as a scrubber for aiding in the dislodgement of fine particles on the paper.

As illustrated in Figures 1 and 2, the attachment is so disposed that the paper travels from the compressed air pipe toward the suction pipe. This, however, may be reversed with the paper travelling in the opposite direction.

By the use of the invention, long runs on presses are possible without stopping to clean rollers and printing surfaces. The effectiveness of removal of particles from the paper will be determined by such factors as speed of the paper past the atachment, density of anti-offset material or other dirt, thevalues of compressed air and suction pressures available at the nozzles. By virtue of the invention, it is possible to make the runs long enough so that any stoppage for cleaning is negligible in comparison to the running time.

What is claimed is:

1. Apparatus for removing dirt from paper as it is being fed to a printing press, said apparatus comprising means for feeding and guiding a web of paper, an elongated metal housing having a U shaped cross section, said housing having the length thereof extending across the web, felt strips disposed on the insides of the arms of the U and extending beyond the free edges of the housing, said housing being open only at the side opposite the bottom of the U, a compressed air pipe disposed within said housing along one side thereof and having air discharge openings facing the paper, said air discharge openings extending along a line across the web and being so oriented as to also face the opposite side of the housing, a suction pipe of substantially larger cross sectional area than the air pipe disposed within the housing and separated from the air pipe, said two pipes extending across the web, said suction pipe having the portion facing the paper bulged out toward the paper, said suction pipe having suction openings only along a narrow region extending the full length of the suction pipe with the openings being disposed in the portion of the pipe between the adjacent housing side and the said bulged out part of the pipe so that the suction openings face the adjacent felt strip, the housing providing a substantial region within the housing and outside of the two pipes, said region having substantial width and depth whereby air emerging from the compressed air pipe will dislodge dirt from the paper surface and the suction slots will remove the same.

2. The construction according to claim 1 wherein said apparatus is mounted to provide a clearance from the paper of about Me of an inch.

3. Apparatus for removing dirt from paper as it is being fed to a printing press, said apparatus comprising means for feeding and guiding a web of paper, an elongated metal housing having a U shaped cross section, said housing being open only at the side opposite the bottom of the U, means for supporting said housing so that the open side thereof is in proximity to the web with the web disposed generally parallel to the housing bottom wall, a compressed air pipe disposed within said housing along one side thereof and having air discharge openings facing the paper and in the direction of travel of the paper, a suction pipe of substantially larger cross sectional area than the air pipe disposed within the housing and separated from the air pipe, said two pipes extending generally parallel to the web and across the width thereof and being disposed against the housing side walls to leave a free region within the housing between the two pipes, said suction pipe having the portion facing the paper bulged out toward the paper, said suction pipe having suction openings only along a narrow region extending the full length of the suction pipe with the openings being disposed in the portion of the pipe between the adjacent housing side and the said bulged out part of the pipe so that the suction openings face the housing edge, the housing providing a susbtantial region within the housing and outside of the two pipes, said region having substantial width along the direction of web travel and depth in a direction away from the web whereby air emerging from the compressed air pipe will dislodge dirt from the paper surface and the suction slots will remove the same.

4. The construction according to claim 1 wherein said suction and compressed air pipes have circular cross sections.

5. The construction according to claim 1 wherein the two pipes are so disposed that the web travels from the compressed air pipe toward the suction pipe.

6. The construction according to claim 1 wherein said metal housing has a dimension along the length of travel of the web which is between about 1 /2 and 2 times the dimension between the bottom and open side.

References Cited in the file of this patent UNITED STATES PATENTS 345,610 Wood July 13, 1886 1,136,434 Overholt Apr. 20, 1915 1,211,902 Warner Jan. 9, 1917 2,022,593 Fuykers Nov. 26, 1935 2,082,411 Merrill June 1, 1937 2,274,641 Abbott et al. Mar. 3, 1942 2,499,572 Dunakin et a1 Mar. 7, 1950 

